1. Field of the Invention
An embodiment of this disclosure relates to a nonvolatile memory device and a method of operating the same and, more particularly, to a nonvolatile memory device capable of checking a pass or fail of a memory cell in response to a column address, and a method of operating the same.
2. Description of the Related Art
Recently, demand has increased for nonvolatile memory devices which can be electrically programmed and erased, and which do not require a refresh function for rewriting data at specific intervals.
Each of the memory cells of a nonvolatile memory device is an electrically programmable and erasable element. The program and erase operations of the memory cell are performed in such a way that electrons are moved by a strong electric field supplied to a thin oxide layer of the memory cell, thereby shifting a threshold voltage of the memory cell.
During a program operation of a nonvolatile memory device, a verify operation is performed for checking whether target program cells have been programmed with a verify voltage or a higher voltage. Cells on which a program operation is no longer needed to be performed because the cell passed a verify operation are treated as pass cells. Cells on which a program operation has not been completed are treated as fail cells and are subjected to an additional program operation.
It is necessary to check the number of fail cells within one page in accordance with an operation of a nonvolatile memory device. To this end, a pass/fail circuit outputs a fail signal when the number of fail cells within one page is greater than the number of allowed error correction code (hereinafter referred to as ‘ECCs’) bits and outputs a pass signal when the number of fail cells within one page is smaller than the allowed number of ECC bits.
When performing a pass/fail check operation using a pass/fail circuit during a program operation, a known nonvolatile memory device classifies a plurality of page buffers by group and sequentially performs the pass/fail check operation by group. In this case, page buffers placed in adjacent regions are grouped into one group.
In the pass/fail check operation using the known pass/fail circuit, however, an operation of checking an address again is necessary in order to determine whether an error can be corrected because the number of fail bits is counted within a page buffer grouped according to page buffer positions. This is because data must be selected based on a column address and then checked within a specific range in order to determine whether an error can be corrected.